An age old problem in retail sales is shoplifting or theft. A modern method of dealing with this problem is the use of electronic article surveillance tags and labels, and associated detection systems. Generally, these tags and labels have small, passive electronic circuits enclosed within them, and the tags or labels are attached to merchandise in the store. The detection system includes various types of antennas located at store exits or other areas where security is desired. Transmitting antennas broadcast a signal of a specific frequency into the security zone, and if any EAS tag or label is in this area, its passive circuitry is excited, producing a signal. The signal broadcast by the transmitting antenna is sometimes called an interrogation signal, and it is tuned to a frequency that will produce a signal from the EAS tag or label that is strong enough to be detected by receiving antennas, also located at the security zone. This responding signal is a resonant response characteristic of the circuitry of the EAS device and is a multiple of the interrogation signal. Detection of an EAS signal within the security zone cues the system to emit an alarm to alert store employees or security.
It is highly undesirable to have alarms sound when merchandise that has been appropriately paid for is being removed from the store. Two typical approaches to prevent this problem are removing the EAS device at the check-out counter or leaving it attached to the merchandise and deactivating it there. The method of deactivating the EAS device depends on the particular elements in the passive circuit. If the circuit includes a capacitor, it may have an excessive voltage induced to break down the dielectric, or, similarly, a high voltage or static discharge may be used to destroy a diode, if present in the circuit. Destroying these elements also destroys the passive circuit. Some EAS devices utilize components which have magnetic characteristics, and some of these are deactivated by giving these components a magnetic bias which significantly changes the circuit's behavior, but more typical, is the use of a process called degaussing to demagnetize a circuit element having a magnetic characteristic. Degaussing entails exposing a magnetized object to an alternating magnetic field and then attenuating the magnitude of the field gradually to zero. Simply turning off the field will not degauss the object. Typically, this field is generated by passing a current through an electrical coil. In this case, degaussing the magnetic element changes the passive circuit enough that its resonant response to the interrogation signal is not detected by the receiving antennas in the system. Associated with the deactivation coils must be a means of triggering the deactivation cycle. Most often, this is a localized detection system similar to those detection systems placed for security, but specifically associated with the deactivation coil. Other triggering means include optical sensors and manual activation. The present invention is a method and apparatus for degaussing magnetic elements in these types of EAS devices, especially the extremely inconspicuous EAS labels.